Azolla pinnata
Encyclopedia
Azolla pinnata is a species of fern
known by several common names, including feathered mosquitofern and water velvet. It is native to much of Africa, Asia from China
to Japan
, India
and the Philippines
, and parts of Australia. It is an aquatic plant
, its frond floating upon the surface of the water. It grows in quiet and slow-moving water bodies, because swift currents and waves break up the plant.
This is a small fern with a triangular frond measuring up to 2.5 centimeters in length which floats on the water. The frond is made up of many rounded or angular overlapping leaves each 1 or 2 millimeters long. They are green, blue-green, or dark red in color and coated in tiny hairs, giving them a velvety appearance. The hairs make the top surface of the leaf water-repellent, keeping the plant afloat even after being pushed under. A water body may be coated in a dense layer of the plants, which form a velvety mat that crowds out other plants. The hairlike roots extend out into the water. The leaves contain the cyanobacterium Anabaena azollae, which is a symbiont
that fixes nitrogen
from the atmosphere that the fern can use. This gives the fern the ability to grow in habitats that are low in nitrogen.
The plant reproduces vegetatively
when branches break off the main axis, or sexually
when sporocarps
on the leaves release spores.
It is present in New Zealand
as an introduced species
and an invasive weed
that has crowded out a native relative, Azolla rubra. It is a pest of waterways because its dense mats reduce oxygen in the water. The weevil
Stenopelmus rufinasus is used as an agent of biological pest control
to manage Azolla filiculoides
, and it has been found to attack A. pinnata as well.
Rice farmers
sometimes keep this plant in their paddies because it generates valuable nitrogen via its symbiotic cyanobacteria. The plant can be grown in wet soil and then plowed under, generating a good amount of nitrogen-rich fertilizer
. The plant has the ability to absorb a certain amount of heavy metal pollution, such as lead
, from contaminated water. It is 25-30% protein and can be added to chicken feed
.
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
known by several common names, including feathered mosquitofern and water velvet. It is native to much of Africa, Asia from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, and parts of Australia. It is an aquatic plant
Aquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
, its frond floating upon the surface of the water. It grows in quiet and slow-moving water bodies, because swift currents and waves break up the plant.
This is a small fern with a triangular frond measuring up to 2.5 centimeters in length which floats on the water. The frond is made up of many rounded or angular overlapping leaves each 1 or 2 millimeters long. They are green, blue-green, or dark red in color and coated in tiny hairs, giving them a velvety appearance. The hairs make the top surface of the leaf water-repellent, keeping the plant afloat even after being pushed under. A water body may be coated in a dense layer of the plants, which form a velvety mat that crowds out other plants. The hairlike roots extend out into the water. The leaves contain the cyanobacterium Anabaena azollae, which is a symbiont
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
that fixes nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
from the atmosphere that the fern can use. This gives the fern the ability to grow in habitats that are low in nitrogen.
The plant reproduces vegetatively
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
when branches break off the main axis, or sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
when sporocarps
Sporocarp (ferns)
A sporocarp is a specialised type of structure found in some ferns whose primary function is the production and release of spores.Among ferns, sporocarps are found only in the three families of the order Salviniales, a group that is both aquatic and heterosporous. The term actually refers to two...
on the leaves release spores.
It is present in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
as an introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
and an invasive weed
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
that has crowded out a native relative, Azolla rubra. It is a pest of waterways because its dense mats reduce oxygen in the water. The weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
Stenopelmus rufinasus is used as an agent of biological pest control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
to manage Azolla filiculoides
Azolla filiculoides
Azolla filiculoides is a species of Azolla, native to warm temperate and tropical regions of the Americas as well as most of the old world including Asia and Australia....
, and it has been found to attack A. pinnata as well.
Rice farmers
Paddy field
A paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...
sometimes keep this plant in their paddies because it generates valuable nitrogen via its symbiotic cyanobacteria. The plant can be grown in wet soil and then plowed under, generating a good amount of nitrogen-rich fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
. The plant has the ability to absorb a certain amount of heavy metal pollution, such as lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, from contaminated water. It is 25-30% protein and can be added to chicken feed
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
.